Simulation modelling to validate the flow method for estimating completeness of case ascertainment by cancer registries.

Background: To validate estimates of completeness of cancer ascertainment obtained by the flow method.

Methods: We generated a computer simulation of patient-level cancer registration processes, based loosely on the age distribution and survival of colorectal carcinoma patients, and utilizing a mixture of 'cured' and 'killed' subjects with an age-dependent fraction of 'cured' cases. The simulated data were then used in an analysis of completeness using the flow method.

The effects of twins, parity and age at first birth on cancer risk in Swedish women.

The effect of reproductive history on the risk of cervical, colorectal and thyroid cancers and melanoma has been explored but the results to date are inconsistent. We aimed to examine in a record-linkage cohort study the risk of developing these cancers, as well as breast, ovarian and endometrial cancers, among mothers who had given birth to twins compared with those who had only singleton pregnancies. Women who delivered a baby in Sweden between 1961 and 1996 and who were 15 years or younger in 1961 were selected from the Swedish civil birth register and linked with the Swedish cancer registry.

Completeness of ascertainment by cancer registries: putting bounds on the number of missing cases.

Background: When comparing cancer incidence or mortality rates between different regions, it is important to know how complete the registration data are on which these figures are based. A number of ways of estimating completeness have been proposed, but it is often difficult to say how precise these estimates are. We describe a computer program developed to produce measures of precision for estimates of completeness obtained by one such method, the flow method.